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Predicted Transmitting Ability (PTA) is the average genetic value for a given trait that an animal transmits to its offspring. The transmitting ability of a trait may be predicted with a certain degree of confidence (called Reliability).

The USDA animal model genetic evaluation system (see VCE Publication 404-086) uses statistical procedures to evaluate the impact of different factors on production records of a single goat. The factors are effects of management group (herdmates to the goat), the additive or heritable part of genetic differences between goats, effects in common with other paternal half sisters in the same herd, permanent environmental effects that act on all lactations of one goat, and everything that is left over. Published genetic evaluations are called PTA's, and are half of the additive genetic value for a dam or sire. Genetic merit for each trait is halved because the purpose of PTA is to predict the part each parent transmits to progeny.

PTAs are calculated for production traits (milk, fat, fat%, protein and protein%) twice per year. PTAs are also calculated for type traits (13 linear traits and final score) once per year after ADGA Linear Appraisal is complete and recorded.

PTAs are the basis for the Production Type Index (PTI) and Estimated Transmitting Ability (ETA).

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